In the lifting of heavy, bulky equipment a crane normally provides a single load line which branches at a bridle and attaches in two portions to an elongated bar known in the art as a spreader bar. The spreader bar has one or more depending load lines which lower from its ends and affix to a piece of equipment to be lifted. This apparatus per se and the use of spreader bars is generally known in the art.
Spreader bars are normally constructed to fit a piece of equipment of a given load and dimension, and thus cannot be reused except on a piece of equipment of similar dimension and equal or lesser load. Attempts have been made in various U.S. patents to teach a method for providing an adjustable spreader bar which could be used over a variety of spreader lengths.
In U.S. Pat. No. 4,128,267 entitled "Lifting Beam" there can be seen a lifting beam comprising an elongated member carrying one or more pivotally mounted hooks for engagement of a load to be lifted. A balance weight is provided on the hooks to lie on either side of the pivotal axis thereof so as to cause the hood to be biased into or from engagement of the load to be picked up or released when the beam is lowered on to same.
In U.S. Pat. No. 4,136,903 there an be seen a "Tire Lifting Apparatus" which comprises a master support sleeve, two movable arms slideably associated therewith, and two hook units pivotably connected to the arms for easy engagement with the inner rim of a tire.
A "Handling Beam for Heavy Elongate Objects" can be seen in U.S. Pat. No. 3,762,756 which comprises a simple and reliable missile handling beam assembly readily engageable with conventional missile supporting lug arrangements. The assembly does not impose any stress on the object being handled, since a lifting hook can be located in a position closest to the center of gravity of the load, hence the attitude of the object can be easily controlled during the lifting and lowering movements.
In U.S. Pat. No. 4,258,949 entitled "Extensible Spreader Frame for Cargo Containers" there can be seen an extensible lifting spreader frame comprising a pair of oppositely extending beam arms slideably received within a central pair of side-by-side connected sleeve beams. Beam cross arms at the outer ends of the sleeve beams mount twist-lock latching hooks at their opposite ends for attachment to the four socketed top corners of a cargo container to be lifted.
A "Sling Mounting Head" for use with a spacer element and mounting two members of a sling chain can be seen in U.S. Pat. No. 4,215,891. The sling mounting head has a body portion including a central section, and first and second end sections extending from the central section.
In U.S. Pat. No. 3,206,243 issued to B. F. Miles on Sept. 14, 1965, there is seen a "Spreader Bar" apparatus.
U.S. Pat. No. 3,010,751 entitled "Adjustable Lift Hooks" issued on Nov. 28, 1961 to E. J. Day, et al.
A "Sling Carrier" device is seen in U.S. Pat. No. 3,252,729 which issued on May 24, 1966, to R. A. Holmes.
Many of these devices are highly complex in nature and because of their construction would necessarily be limited to relatively small loads.
Thus, there is a need for a simple, easy to use, easy to construct spreader bar which could easily be adapted to a variety of load and dimensional situations.